What question did this study set out to answer?

This study aims to explore the relationship between cardiorespiratory fitness and cardiac structure and function in firefighters.

May 14, 2026

Associations between cardiorespiratory fitness and cardiac function in firefighters

Key Points

This study aims to explore the relationship between cardiorespiratory fitness and cardiac structure and function in firefighters.
Forty-five firefighters underwent a cardiac assessment via echocardiography and a maximal exercise treadmill test.
Cardiac assessments included left ventricular end-diastolic diameter, stroke volume, ejection fraction, and left ventricular mass indexed to body surface area.
The study accounted for age, sex, and BMI in the analysis.
Higher cardiorespiratory fitness correlated with increased stroke volume (B=0.95, p=0.03) and left ventricular mass index (B=1.61, p=0.048).
No significant associations were found with systolic or diastolic function after adjustments.
These findings suggest cardiorespiratory fitness positively influences cardiac structure, supporting cardiovascular health in firefighters.

Abstract

Firefighters are at an elevated risk of cardiovascular events, often attributed to the strenuous, high-intensity workloads and heat stress that acutely elevates cardiovascular strain. Higher cardiorespiratory fitness directly benefits cardiac structure and function in the general population and thus could attenuate cardiovascular strain. The purpose of this study was to examine the association between cardiorespiratory fitness and cardiac structure and function in firefighters. Methods: Forty-five firefighters (6 females, 40 ± 10 yrs, 29.2 ± 4.5 kg/m 2 , 23.4 ± 6.7% body fat) underwent a cardiac assessment via echocardiography at rest to determine left ventricular end-diastolic diameter indexed to body surface area (LVEDDi), stroke volume (SV), ejection fraction (EF), relative wall thickness (RWT), left ventricular mass indexed to body surface area (LVMi), and diastolic function (E/A and E/e’ ratios). Cardiorespiratory fitness (VO2peak, ml/kg/min) was assessed via a maximal exercise treadmill test. Results: VO2peak was significantly correlated with E/e’ (-0.438, p=0.003), SV (0.375, p = 0.02), and LVMi (0.451, p =0.01). After adjusting for age, sex, and BMI, only SV (B=0.95, p=0.03) and LVMi (B=1.61, p=0.048) remained significantly associated. Conclusion: In our cohort of career firefighters, greater cardiorespiratory fitness was associated with higher stroke volume and left ventricular mass index. We did not observe any significant associations with systolic or diastolic function after adjustments, which could be due to the overall healthy values observed within this cohort. Overall, higher cardiorespiratory fitness was associated with beneficial changes in cardiac structure and function, supporting the importance of aerobic fitness for cardiovascular health in the fire service. This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.

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